Power tension elevating device



Dec. 18, 1951 E. WOLDRING 2,578,371

POWER TENSION ELEVATING DEVICE I Filed July 15, 1946 Z SHEETSSHEET l\NVENTOB WW Dec. 18, 1951 E. WOLDRING 2,578,871

POWER TENSION ELEVATING DEVICE Filed July 15, 1946 2 SHEETS SHEET .2

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Patented Dec. 18, 1951 UNITED STATES PATENT OFFICE POWER TENSIONELEVATIN G DEVICE partnership Application July 15, 1946, Serial No.683,719

The present invention relates to a power tension elevating device. It isprimarily designed for the purpose of moving and elevating goods from alower to a higher position by means of an endless conveyor belt, theupper run of which carries the goods and has an upward inclination, theangle of which may be varied, so that goods placed at the lower part ofthe device, are moved upwardly with the belt and away from the positionwhere loaded on the belt to desired elevated positions.

Such type of device is subject to different loads carried, with theresult that the section or upper run of the belt which carries theloads, has a tendency to sag between the lower and upper rollers overwhich it runs, with greater sag with the greater loads. With myinvention, the conveying belt is power driven and a novel constructionis provided such that upon increase of load carried by the belt, thisrequiring an increase in power to drive said belt, the belt isautomatically tensioned to a greater degree, thus compensating for andovercoming entirely or in large measure, the sagging of the upper run ofthe belt which is carrying the load of goods being elevated.

My invention is directed to a very novel, compact and effective powerdriven transmission of a belt conveyor for increasing the tension of thebelt with increases of loads carried thereby. The belt at all times issubjected to a normal tension, but upon increase in the weight of theload carried, such tension is increased and the run or section of thebelt to which the load is directly applied, has its tension increased,also the belt is decreased in tension upon lessening the weight of theload, whereby by means of my invention, the belt as to tension is madeself-corrective for all conditions of-all operation with respect to theload which is being elevated thereby.

An understanding of a preferred construction embodiment of the inventionmay be had from the following description, taken in connection with theaccompanying drawing, in which:

Fig. 1 is a side elevationof a machine made in accordance with myinvention, I

Fig. 2 is a fragmentary enlarged'similar section of the lower portion ofthe machine, and

Fig. 3 is a fragmentary plan view of the machine at the lower endportion thereof, a part of the conveyor belt being broken away forbetter disclosure.

Like reference characters refer to like parts in the different figuresof the drawing.

In the construction disclosed, the conveyor frame preferably-has spacedsides,-each includ- 5 Claims. (01. 198208) ing an upper bar I of metalof a suitable angular cross section and a like lower bar 2, said barsdiverging from each other toward the lower end of the machine. At theirupper ends the bars are connected together and the sides of the conveyorframe may be secured together at their upper ends by a transverse plate3. Suitable braces 4 interposed between the side bars I and 2 betweentheir ends may be used and, of course transverse connecting members maybe used, each to connect the two sides of the frame together. Both ofsaid upper and lower bars I and 2 at their lower ends are connected withend plates 5 of a generally semi-circular form, between which tubularcross rods 6 extend, secured at their ends to the plates, to make astrong relatively light rigid frame construction.

A lower tubular bar I likewise extends between the plates 5 and to ittubular rods 8 may be secured which extend forwardly in a generallyhorizontal direction and receive telescopically therein rods or tubes.Said tubes 8 and 9 may be adjusted to different positions relative toeach other and held in any selected position .by any suitable releasablesecuring means. The rods 9 at their forward ends are connected to ahorizontal axle l0 upon which end wheels II are mounted. Tubular rods l2are also connected at their lower ends to the axle l0, and extendupwardly in a forwardly inclined direction and telescopically receivetubes or rods l3 therein, the upper ends of which are connected with theframe of the machine near its upper end. The telescopic parts l2 and I3may likewise be adjusted to different positions with respect to eachother and releasably held in any selected position. Therefore, theinclination of the frame to the horizontal is subject to a relativelywide range of adjustment.

A drive roller I4 is mounted on a central hori zontal shaft [5, saidshaft being substantially midway between the upper and lower edges ofplates 5. A U-shaped fork or stirrup !6 has the arms thereof connectedat the ends of the shaft l5. From the cross connecting portion of thestirrup It, a frame I I extends forwardly, the front end of the framereaching approximately to mid-position of the first described mainconveyor frame and having a pivotal connection at is to suitablesupporting blocks I!) carried by the main frame.

An electric motor .29, or other suitable prime mover, is mounted ontheframe ll at its upper end and through a series of sprocket wheels andchains 2| and 22, may drive the roller I4 at a much reduced speedcompared to the speed of rotation of the motor. At the upper portion ofthe main frame above and slightly forward of the roller M, an idleroller 23 on a horizontal shaft is mounted between the plates 5, itsuppermost points being located a short distance above the adjacent uppersides or edges of the upper main frame bars I. A roller 24 is mounted atthe upper end of the main frame. Around the drive roller l4 and the twoidle rollers 23 and 24 an endless conveyor belt 25 extends. Preferablyat its outer side it is equipped with a plurality of spaced transverseslats or ribs, as shown.

The weight of the frame H, the roller I4 and the other associate partscarried by the frame tensions the belt to some extent but such tensionis increased. Rods 26 have around each of them, between their ends, acoiled compression spring 21, the upper end engaging against a washerand nut 28, and the lower end against a shelf 29, one extending fromeach side of the frame I?! throughwhich the lower ends of rods 26 pass.The upper ends'of the rods bear against a transverse frame member 39extending between the upper bars I of thewmain frame. Said springs 27increase the tension in the belt and itmay be varied by adjusting thenuts 28 to normally take care of stretching or wear which occurs.

With the construction described, the goods to be moved and elevated willbe placed upon the upper run or section of the belt conveyor 25 adjacentthe roller 23. The weight of the goods puts a strain upon the beltconveyor so that if the roller It had its shaft 15 fixed at its ends oronly movable a limited distance, the upper run of the belt 25 under theweight of the goods carried would sag between the rollers 23 and 24 withthe greatest degree of sag substantially midway between said rollers.The movement of the upper run of the belt being away from the roller 23the rotation of the driving roller I4 is in a clockwise direction tocause such movement. It drives the belt by frictional engagementtherewith. Such rotation of the roller 14 in said direction and thefrictional engagement of the roller with the belt. tend to cause theroller and the frame I! to move in a downward direction about the axisof the pivots 18. The downward movement increases the tension on thebelt and to a large degree, eliminates the sag in the upper run or,section of the conveyor. Further, because with an increase in weight ofgoods carried, the power required to be delivered to the roller I4 isincreased, the frictional engagement of the roller with the belt 25 willlikewise be increased. with an increase in tension in the belt. Thus thebelt tension is increased with an increase in .the load carried, tothereby maintain the upper run of ,the belt in a taut condition and witha substantially complete ehmination of movement sag therein. Thefloating drive roller M at the inner side of the belt, through itsability to move downwardly, and its frictional pull upon the lower runof the belt causing it to thus move in proportion to the powertransmitted to the roller through the belt, serves to balance againstthe sagging of the belt under the weights carried, greater weights orloads causing a proportionately greater pull on the belt-to remove suchsag.

The construction described is very practical and effective, very usefulin service and is readily and economically produced.

The invention is defined in the appended claims and is to be consideredcomprehensive f all forms of structure coming within their scope.

I claim:

1. A structure as described comprising an elongated frame support, meansfor maintaining said frame support in an inclined position with one endhigher than the other, an idle roller mounted to turn about a horizontalaxis at the higher end of said frame, a second idle roller mounted toturn about a horizontal axis at the upper side of and adjacent the lowerend of the frame, a driving roller located at the lower end of the framebelow the second idle roller, means for driving the driving roller,means on which the driving roller is mounted movably connected with saidframe whereby the driving roller may move in a generally verticaldirection with reference to its adjacentidle roller, and an endlessconveyor belt passing around all of said rollers, the pressure of thedriving roller acting against said conveyor belt to impart tensionthereto, said driving roller f-rictionally driving said conveyor beltand automatically moving in a downward direction upon weight'applied tothe belt at-the upper side thereof between said idle rollerstherebyincreasingthe tension in the belt with increases of said weight.

2. In a structure as described, an elongated frame, means for adjustablysupporting said frame in a position inclined to the horizontal with oneend higher than the other, an idle roller mounted to turn about ahorizontal axis at the higher end of the frame, a second idle rollermounted to turn about a horizontal axis at the upper side of andadjacent the lower end of the frame, a driving roller mounted to turnabout a horizontal axis, an elongated support at one end of which thedriving roller is mounted, means pivotally connecting the oppositeend'of said support to the frame at anintermediate' position inthelength of the frame, means for'continuously driving said driving roller,and an endless conveyor belt passing: around all of the rollerslengthwise of said frame at its upperside and within which said drivingroller is located in frictional driving engagement therewith.

3. A construction as defined in claim 2, saidmeans for driving thedriving-roller comprising a prime mover mounted 'uponsaid support forthedriving roller adjacent its pivotally connected end, and speedreducing driving means between said prime mover and driving roller.

4. In a construction as described, an elongated supporting frame, meansfor adjustably elevatingone end of the frame to a higher level than theother end, an idle roller at the higher end of the frame mounted to turnabout a horizontal axis, a second idle roller mounted to turn on ahorizontal axis adjacent the other end of the frameroller to the upperidle roller, the frictional engagement of said driving roller with saidbelt varying with loadapplied to the upper run of the belt whereby thetension of the belt is increased by said engagement of the drivingroller therewith, upon increasesof loads carried from adjacent the loweridle roller to the higher idle roller.

5. A structure as described comprising, an elongated support having areceiving end, and.- a

5 delivery end, leg means for supporting said delivery end at a higherlevel than the receiving end, a first idle roller mounted at saiddelivery end of the support, a second idle roller, said second rollermounted at the receiving end of the support, a driving roller below andadjacent said second idle roller and positioned outwardly therefrom in adirection away from said first idle roller, means for driving saiddriving roller, an endless conveyor belt passing around all of saidrollers, and means for mounting said driving roller for up and downmovements toward and away from said second idler roller, combined withmeans acting upon said driving roller normally tending to move it awayfrom said second idle The following references are of record in the fileof this patent:

FOREIGN PATENTS Country Date Great Britain Mar. 7, 1919 Number

